Development of a pico-satellite : star tracker for attitude determination

Abstract

A star tracker is a satellite-based embedded system which makes use of photocells or sensors to measure the positions of stars and hence the orientation of the satellite in space. This information is essential for any space mission, as it supplies all attitude data required for satellite control.

While there are other sensors used for the same purpose, star trackers work on a fully autonomous manner and are more accurate and precise in attitude determination.

A star tracker consists of 2 major components: the onboard camera and the onboard processing algorithm.

In this project, images will be captured using the Micron Imaging MT9M032 CMOS Active Pixel Sensor (APS) and processed using the Pyramid star identification algorithm to identify the co-ordinates of the stars and hence that of the satellite for attitude determination. Developed together with the K-vector method, this algorithm serves to speed up the total processing time.

The use of CMOS APS technology also allows the possibility to construct smaller and lighter star trackers that consume even lower power than conventional ones, making it an important consideration for microsatellite applications.